A Brief Discussion on the Use and Maintenance of the Gas Line System in Domestic QLB Asphalt Mixing Plants

1. Ensure the sealing of all connection parts of the gas path

If air leakage is found at the pipe joint and in the pipeline, it should be eliminated in time to avoid the waste of compressed air and increase the working load of the air compressor.

To ensure that the air compressor operates in the best condition, the following aspects should be achieved:

① Precautions before use: The air compressor should be placed horizontally and the oil level of the lubricating oil should be checked. Adjust the upper and lower limit values of the automatic air pressure switch properly (generally, 4.5Mpa-7.5Mpa is recommended). If the pressure is too low, the power cylinder will act slowly; if it is too high, it will be unfavorable for the sealing parts of the airway system. Check the tension of the drive V-belt. When pressing the V-belt with your thumb with a force of 15Kg·f, there should be a deflection of 1.5cm to 2cm. When replacing the three-angle belt, the entire set should be replaced to ensure consistent tension.

During work, maintenance personnel should constantly inspect to observe whether the upper and lower limit values of the air pressure automatic switch that have been adjusted are effective, check for any air or oil leakage, and detect any abnormal sounds. If any abnormal phenomena are found, the machine must be stopped immediately for maintenance.

After the machine stops, the oil and water in the air storage tank should be drained in time to prevent them from entering the air pipeline. Check the oil level of the lubricating oil in a timely manner. If it is too low, add it promptly. It is recommended to change the lubricating oil every 80 to 100 hours. If the working environment is harsh, shorten the oil change cycle. 40CD diesel engine oil is sufficient as the lubricating oil. The air filter element should be cleaned every 50 hours. If cleaning is ineffective, it should be replaced in time. (For paper filter elements, simply blow them clean from the inside out with compressed air; if it is a sponge-filled filter element, clean it with detergent and air dry it.) The air filter element cannot be ignored. If the air filter element is too dirty, it will cause the air entering the compressed cylinder to contain excessive floating dust, accelerating the wear of the empty cylinder and piston rings, and is prone to form carbon deposits, affecting the sealing performance of the intake and exhaust valves. In severe cases, it may even cause cylinder pulling and gas leakage, leading to contamination of the lubricating oil and affecting the lubrication effect. While gas leakage occurs, oil supply will also happen. If the gap between the cylinder wall and the piston ring is too large, contaminated lubricating oil will seep into the compression chamber and form an oil mist, thereby contaminating the compressed air.

Ensuring that the output pressure of the air compressor is balanced and that the compressed air is clean and pollution-free is the prerequisite for ensuring the normal operation of other components and extending their service life.

3. Pay attention to the functions of oil-water separators and oil misters

The function of installing an oil-water separator and an oil mist lubricator in the gas line system is to filter out the moisture and oil stains in the compressed air and ensure that the compressed air contains a small amount of clean oil mist, so as to guarantee the good operation of the solenoid valve and the power cylinder. Therefore, it is necessary to clean the oil-water separator in a timely manner and ensure that the oil mist lubricator is not short of oil. Especially when the air compressor has slight wear and the compressed air is contaminated, the role of the oil-water separator becomes more prominent. Once it is found that the oil-water separator has failed to work, it must be replaced in time. The capacity of the oil mist lubricator's oil storage cup is calculated at 100ml. It is advisable to use it for 100 hours. Ordinary diesel engine oil can be selected as the oil type.

The correct use and maintenance of solenoid valves and power cylinders

During operation, if the pressure output by the air compressor is balanced, the power cylinder should quickly and accurately switch on and off the power supply of the solenoid valve. If the operation is not flexible, first check whether the solenoid valve is leaking. If the solenoid valve is working normally, it is the power cylinder itself that is leaking.

The leakage of an electromagnetic valve refers to the phenomenon where there is air leakage at the two exhaust ports on one side of the air inlet when it is not in operation (the air pressure is within the standard range). The repair method is to disassemble the solenoid valve, clean all the components thoroughly with clean diesel, dry them with clean cotton yarn and apply a small amount of clean engine oil on the surface before reassembling.

There are two types of air leakage in power cylinders: internal leakage and external leakage. Internal leakage refers to severe wear of the piston assembly components inside the cylinder, causing air to flow between the front and back of the piston. At this time, it will affect the speed of the cylinder's operation, and in severe cases, it may cause the switch to fail to operate properly. External leakage refers to severe wear of the seal at the movable pull rod, which can cause the pull rod to return slowly or even fail to return properly. As long as you understand the part where the fault occurs, the repair will be handled with ease.

If the power cylinder is not in operation for a long time, a small amount of engine oil should be injected at the two pipe joints to prevent internal corrosion. A layer of grease should be applied to the surface of the movable pull rod to prevent rust.